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Date:   Fri, 3 Jul 2020 08:00:13 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Chris Dickens <christopher.a.dickens@gmail.com>
Cc:     linux-usb <linux-usb@vger.kernel.org>,
        Felipe Balbi <balbi@kernel.org>, andrzej.p@samsung.com
Subject: Re: gadget: Why do Microsoft OS descriptors need their own USB
 request?
Message-ID: <20200703060013.GA6188@kroah.com>
References: <CAL-1MmUi6OajEYNuP+OOEeekesZJjAGP-8VDSjGydXAMEFHhMA@mail.gmail.com>
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On Thu, Jul 02, 2020 at 05:11:11PM -0700, Chris Dickens wrote:
> Hi,
> 
> I've never understood it, so I figure I might as well just ask.  Why
> does the Microsoft OS descriptors support require the allocation of a
> separate USB request for the composite gadget device?  Both the
> default control request buffer and the "special" OS descriptors buffer
> are the same size (4KB) and use the same completion handler.  As far
> as I can tell there is nothing distinct between them.  There's only
> ever one outstanding USB request queued to ep0, so can the dedicated
> USB request be removed and just share the default one?  I'm happy to
> provide a patch, unless of course I've missed something.

Try it and see, I think it was needed for some reason, but look at git
history to be sure.

thanks,

greg k-h